LED Grow Lights – Do they actually work?

Evidence. It’s what we all need to see when claims start to circulate regarding something revolutionary, something game-changing, something that on the surface of our understanding sounds far too good to be true! And yet, more often than not, word of mouth can spread like wildfire without actual proof of results ever being present, a facet of modern times largely down to the fast and open nature of the Internet.
For most members of the indoor gardening community, the repeated boasts of “superior technology” and “enhanced plant growth” made by manufacturers of LED grow lights certainly seem attractive and plausible. But where are the reports on research and testing, the side-by-side comparisons with existing lamps, the clear, concrete, undeniable evidence? Have a look... we can't find any!
Keith sets out to throw light on this issue in a series of articles examining the effects of using various LED units to raise plants at different stages of the life cycle. Join him on his journey!

About a decade ago there were whisperings of a development that would change the world of hydroponics forever. Interest surrounding LEDs – or Light Emitting Diodes – reached an all time high when scientists at NASA started using this new technology, investigating its impact upon plant growth in outer space. For indoor gardeners far and wide, everything seemed to suggest that the lights had the potential to produce great plants whilst simultaneously reducing electricity costs and improving overall efficiency.

Like many members of the indoor growing community, I too got caught up in the excitement. Who wouldn’t welcome a choice of spectrum specific lights costing just a fraction of the price to run compared against existing models? Of course the prices for these LED light systems were initially extortionate, but as is the case with all new technology, the anticipation was for them to soon become affordable to the masses.

Now almost ten years later, you can buy a ‘decent’ LED light system for only £90.

So I bought one.

It claims to be able to outperform a 400 Watt light system, a bold statement that I wanted to put to the test. As I prepared to examine how the LED light performs against other rival products, I thought I’d do a little research beforehand.

After all these years of development and hyperbole you’d expect there to be plenty of proof that LED lights outperform HID’s. Well I looked, and I looked again. NASA did tests, that’s true. However the main result available on their website is taken from a study into LED lights and the healing of human skin cells. The primary experiment in terms of plant growth dealt with raising seeds up to a size of 10mm. There was a picture of a potato plant under LEDs and lots of information about tests planned seven years ago, but no actual results.

I have emailed NASA to see if they could help shed any light on the matter, and will let you know if anything happens. So it was back to the drawing board. Let me tell you, finding legitimate research is difficult! The majority of the articles out there are by LED manufacturers and therefore tend to be a little biased, again providing no actual evidence. Now I am certainly no expert when it comes to internet research, but I can usually find what I want without putting in the hours that I have spent this time round. The truth was proving difficult to find. An example of the extent of the unreliability of information taken from the web was a site saying that LED lights provide both the red light needed for vegetative growth and the blue light for the flowering/fruiting phase. If something so simple in terms of plant requirements is clearly wrong, how then can we be expected to believe anything else they write?

Finally I stumbled across something, a grow diary with LED lights! Not quite the £90 set up I had, more a laboratory-based grow with a $1,200 LED setup. How exciting! So I started reading. Unfortunately within the first few lines the company stated that despite all the claims they had never previously been able to achieve full sized tomatoes with any LED light. That might explain all the broken links where research was promised, and the lack of legitimate studies. If after all these years a laboratory research centre had failed to grow full sized tomatoes, then how can the LED lights out perform HID’s?

Therein lies the biggest problem with the LED lighting industry, it has perhaps been blighted by unrealistic claims. Some of those relating to the 90 Watt system I bought were as follows:

- The G3 LED UFO GROW LIGHT is manufactured using long life LED lights. These lights have a rated life of over 100,000 hours (there are 8,760 hours in a year)

- The G3 LEDs are nearly 100% efficient at plant growth! This is 10 times the efficiency of a Sodium or Halide light!

- Uses only 90 watts but has the output equal to a 400 watt High Pressure Sodium System!

- 80,000 hour life expectancy

- Consuming only 90 watts of power and producing virtually no heat, the G3 LED GROW LIGHT boasts light intensity and growth rates exceeding that of a 400W HPS.

Let’s leave it there, you get the picture. Apart from the conflicting life expectancy of the unit, every bullet point can arguably be contested. In all reality when I bought the light, it was not to outperform a 400 Watt system. Instead I bought this light simply because at £90 it was in the price range of a standard HPS system.

You may think my exploration of the world of LED lights has got off on the wrong foot somewhat, with the initial focus of this article being to identify a large amount of mis-information and general lack of legitimate studies. Nevertheless my aim and intention is to provide a balanced, unbiased series of articles examining whether LED lights actually work in an indoor garden environment. I must admit that I am a little annoyed at the pages and pages of claims that can’t be backed up. In my opinion the truth about LEDs is still largely unknown. That’s why rather than continue to look at the results of other tests, it may be better to simply begin my own.

To try to get a true representation of the current capabilities of LED lights I intend to conduct a series of tests, starting with the most basic and working up to more in depth. It would be churlish of me to put the light side-by-side with a 400 Watt alternative, realise the performance is not similar and dismiss the product out of hand. Of course comparison grows will give us a greater indication of the level of performance, but I want to go further than that. The main emphasis here involves establishing whether they work when it comes to plant growth. If and when that is settled we can look at how they compare against other lights.

UPDATE!

What we’ve learnt so far…

In the first test the 90watt UFO grow light – a widely available LED unit – did manage to maintain several different types of store bought plant over a two-week period of the vegetative stage.

However the similarly efficient 125watt blue Eco-Light that the UFO was pitted against outperformed it for 2 of the 3 plants tested, with the judgement being based on final size and colour.

Code

Price

Qty

1587

125 Watt Blue Eco-Light

£19.95

1588

125 Watt Red Eco-Light

£19.95

From our experience the 125watt blue Eco-Light would have helped raise even better cuttings/seedlings and plants at the very beginning of the life cycle (and the red one works well as a supplementary flowering light), but did that mean the same for the LED unit? We needed to find out…

Due to heat problems, I changed to a hps/LED set up this year. I decided to run a test with 2 tents running clones. I ran 2 identical set ups, 2m x 2m 16 pot DWC, clones from same mothers. 1 tent run 4 x 600hps on smscom 4L, so most of the time 2 lamps were out as the controller turns off lamps to cool the tent down but growth was steady and somewhat predictable and the other tent was running 8 x Prakasa 300w cob LED. Well I've got to say that the LED tent was amazing during veg and although the plants stretched a bit, filled out to be absolute monsters. The problem was when the flowering stage arrived they just didn't cut the mustard and took generally 2-3 weeks to provide 60-70% of the hps yield. My conclusion is that I think there is a definite place for LED, but the technology needs to improve markedly to take the place of HPS. I will definitely keep the LED's but mix the two and use them to supplement HPS during veg only from now on.

Listen guys, if you're growing ornamental plants the best thing to do is to use a dedicated HPS then supplement those with new household COB lights. New COB technology is way better at rendering colours than old cheap older phosphor types. COB's have a better more stable light output and produces red and deep reds better than older kinds. As you know older warm and cool white LEDs were just a blue spike with lots of green, yellow and hardly any red and deep red. Well, the new COB LED lights have much better spectrum that looks golden white instead of sickly yellow orange. Works brilliantly... believe me...

I have been disappointed with commercial LED units, best results so far are with cheap white COB LEDs from eBay. I have tried a 50w chip with a special phosphor mix for growing, it was easily outperformed by a warm white LED. I have tried pulsing the light at 720hz@ 50% duty cycle, that worked for the veg stage but not the flower. My conclusion so far - "For flowers lumens are still king"

Plants have a cycle of growth, which is governed by the wavelength of light. This is because of the type and amount of light that they would get in the wild. Two of these things are Light and warmth.

Red, this is infra red, which has a longer wavelength than red light, and is the type of light that a young plant requires to start its growth. Right from a seed to early life, when a young plant receives filtered light through the taller surrounding plants, in the wild it gets little light other than a changing spectrum from infra-red into the red band of light. It is this wavelength that spurs the plants on to growth.

Blue is the light band going from the blue into the ultra violet. Plants no longer need to grow to get to the light, they need to branch out and get as much of this light as possible.

Red and Blue LED lights have a narrow wavelengths and should not be confused with the full spectrum of light and warmth needed by plants. LED's are made to emit light at a specific wavelength and do not have the range of light a plant would need. To make an LED light unit that would be any good, it would have to be made from lots of different wavelength LED's.

i've payed through the nose for expensive LED lighting which didn't perform well at all. not enough canopy penetration on a flowering crop so not much weight of fruit. i've reverted to HPS but have been watching the progress of plasma lamps and they are now hitting the market at an affordable price. i intend to buy one of these in the near future and if it performs as well as i expect it to will go over completely to plasma within the year.
LED continues to improve and may make a usable growlight eventually but at the moment there is just too much bull around to make a worthwhile evaluation.

ok lets skip the crap for once , led have a place but they are not comparable to hps , heres the issue ,

led use small amounts of elec and can and will create `fruits` to a normal standard , however the wattage is small and so is the area covered , to cover the same area as say a 600hps you will need more than 1 panel so your now using the same amount of elec as a hps , yes the yields will be near as dam it the same but whats the point ? ok theres lack of heat but given its the uk a room will need heating for 8 months of the year so this is not a plus point but a minus , running a 2000w heater to get the temps up is a waste of energy that could have gone into lighting so so much for a saving on elec !, extraction then , yes you dont need to use the same degree of extraction but the cost differences between a 6 inch to 5 inch set up isnt worth mentioning , ok life expectancy ? there simply is no proof to show the led will last longer and given leds dont have a great reputation for longevity then the claims are suspect to say the least , then the cost implication , yes you dont need ballast etc but compared to a digi set up theres not much in it and its a dam site cheaper to replace 20 quids worth of bulbs once a year rather than making out the led will pay for itself in the long run , if it did last the 10 years its hoped then you could easily have 5 hps set ups in that time for the same price and you simply will not get through 5 set ups in 10 years , 2 maybe but not 5 .
so looking at it all leds have a place for sure but they are not a fair comparison to a hps , hps are not better just different , for a micro grow leds are wonderfull but for anything beyond 200w then hps will kick ass

cuttings sprouting in 4 to 5 days? I almost never seen a root come out of a root riot cube in less than 3 weeks, and i have tried all forms of lighting.
I think LED lights are very much down to the quality you buy and at the moment if you get cheap ones then you get cheap results.
Im sure that in time they will crack the problem and produce good quality at a reasonable price.
People get excited about how little power they use but come winter you will find you have heat your grow as the lights will not produce enough heat for the plants so your no better off, but they are a good option in the summer when too much heat can be a problem.

I've used cool and warm white fluorescent tubes for clone rooting as well as HPS lights with more blue in the spectrum. I've tried all sorts of techniques to get fast rooting clones and in my experience the fastest method doesn't really rely on lighting it's down to the environment in which you expect the roots to be produced. I've tried light composts with perlite, rockwool cubes with hand watering, rockwool cubes and nft and rockwool cubes and aeroponics (following the instructions given with the aeroponics kit). All of these gave some success but nothing I found was more reliable and easier to use than aeroponics. If you fill the little baskets with small clay balls, use rooting gel, know which part of the plant to cut for a clone, and then turn it on you should get quick and excellent results - with roots emerging in 3-4 days with the right nutrient mix. By establishing favourable conditions you'll actually need to root prune as well, because once those roots are hanging out of their baskets they will run wild! I wouldn't worry to much about the lighting at this stage - a couple of 2 foot tubes will do the job just fine. Once they are potted on into whatever you prefer growing in then decide which light is for you. My choice is HPS!

Mike brown

Posted April 20, 2013 at 11:14 pm

That story above is not true in my opinion as I have been successfully using an LED light for 18 months. It's a 400 Watt panel, which is equivalent to an 800 Watt hps. Cost me a bit more than a UFO light, but they are rubbish as a main light because the spectrum is not right. The LED panel I'm using has blue spectrum lights for veg, a switch to turn them to red spectrum for flowering, and another switch to make them turbo red for an extra boost in the last 3-4 weeks. I have no heat issues at all and don't need to change bulbs, ballasts, contactors, etc. My results are at least 20% better than using hps and for cuttings I can get roots out of a cube in 4-5 days. I really rate LED's but with so many different models out there, further research on them is required.

You are full of crap! Roots in 4 to 5 days? Yeah right! You really believe LED manufacturers? More fool you for thinking that your 400w LED is the equivalent to a 800w hps. You are exactly the type of person who they aim these products at and are fool enough to buy them. I can guarantee I harvest more product than you with my two 400w hps in a tent.

Loz

Posted January 24, 2013 at 8:47 pm

If you want a cheap grow then go with CFL. You can get a good grow with a 100W in a small area. 400W LED seems stupid. CFL also produces a little bit of heat above the canopy, which is ideal. Give it another 3 to 5 years and I will definitely go LED, but not at the moment.

I agree with John Maguire... for now. There's so many different variations & brands of LED Grow Lights - once the price comes down a tad more I wouldn't mind doing a comparison grow test myself. Have you seen the produce the Americans are growing to the highest levels with a Single 90w UFO?

I've Seen A Few Succesful Grows , Both In The Vegetative And Floral Stages. Fruit Could Have Been Bigger, But Proved Efficient.
Not All Of Us Can Afford £800.00 Lumix LED Plasma Which Are Purported To Be The Future Agro Lights

Like Pete, small plants and fruits - lots of baffling "Pseudo science spiel" about light frequencies etc.
Seems to me luminosity (Power/energy within a given light) is the key.
The plant can't use it if its not there and with most LED rigs on sale at the moment, it just ain't there!.
Good luck to the team, I hope you can prove me wrong..........

If you have a small grow closet and can only use one light that doesn't give off too much heat. I would recommend using a dual spectrum CFL. They have blue and red combined, which look's purple. If you only use red spectrum(2700k) CFL's during flowering, then your flowers and fruits will suffer.

HPS lights are the best and are mostly red spectrum(2100k), but these do have about 25% blue spectrum in them too. That's why you need to get the dual spectrum CFL's!

Nlite Purple 220w £42-£47. Growell should stock these. They do a great job.

We have dabbled with purple CFL's in the past but we found that very few people saw the benefit especially given that they are double the cost of standard CFL's. I'm not doubting that they produce good results (we sold them for around 6 months when they first came out), but we did not find many people willing to part with that kind of cash for a CFL lamp and dropped the product soon after. Maybe in one of our future experiments we can look again at testing the purple CFLs against the standard blue/red.

bob

Posted July 23, 2012 at 8:43 pm

The newer panels are using white leds which seems to defeat the whole purpose of using specific spectrum's for efficiency
these same cree leds are used in high powered flash lights .. perhaps that is where they should stay

the 90w ufo is not even worth testing it is a joke
put it on top of your christmass tree or something

give these panels a test , something more current

SG602
blackstar
MAG 357

people are claiming good results with these panels although the credibility of these "people" can be dubious

Since starting this experiment we have been contacted by a number of LED manufacturers all very keen for us to try their units "that really work". No doubt we will conduct some follow up experiments with some of these and post our results up for all to see. So far, the UFO is not doing so well, but full results update to follow in mid August.

bob

Posted August 20, 2012 at 4:47 pm

Thanks for your reply guys. Anything under 200watts is not worth bothering with from what i hear from those that have tried these LED lights. I really would like to see these panels do well, the lower heat and safety aspect of them is good, but i think the very high cost of them at the moment means they will only appeal to a small section of people. I think it will be a very long time before LED replaces HID, or whether it even will. It seems kind of silly in a way to use a light that consists of 100s of individual lights instead of 1 single bulb lol... is that really progress!?

I know a chap who is achieving good results from induction lamps, perhaps when you guys have finished the LED experiment you can try some of these? I hear they can be quite expensive too.

Keep up the interesting work GroWell team! It will be nice to see some genuine results for once, many of the reports out there on LEDs are from reps of LED companies or people that got discounts to post good reports on them.

flkup

Posted July 23, 2012 at 4:49 pm

Horses for courses
I would of hoped that this was a scrog setup
Stretch under led has been documented before so they seem a poor. Choice for a conventional grow but a small scrog might work

"An example of the extent of the unreliability of information taken from the web was a site saying that LED lights provide both the red light needed for vegetative growth and the blue light for the flowering/fruiting phase."

You might want to swap the RED and BLUE around?!?

I use a 15w LED for my seedlings for around 5-7days.
LED's on large plants are useless.

Hi Matt, that's the point we are making - the manufacturers have got it all wrong so we're dubious about how well their lights will work when they can't even follow the basic principles!

Milo Minderbinder

Posted July 18, 2012 at 2:56 pm

I look forward to the results. I concidererd the UFO myself but was put off by reports of very low yealds and unreliability. Maybe lights that give decent light intensity and growth rates at low running costs are still many years away. Research and development in all areas have been hit hard by the current economic mess.

I have some experience with LED's and I have come to these conclusions.

1) Anything under 250watts is useless.

2) Plants take about 3-4 weeks longer to reach maturity.

3) Yields are typically fairly poor when compared to a HPS grow.

These findings are from doing a back 2 back grow off with a friend for our own evaluation of LED lighting, we both used same subject, similar environment, etc etc, I used a 400watt HPS & my friend used a 250watt LED panel.
I await Keith's findings with great interest.....

I tried my 120watt LED grow light. Poor results. It went back in it's box and can stay there. Yes, they are a LOT cheaper to run and the lack of heat is convenient but my experience is they do not work anywhere near as well as the 400 HID. I was, and still am, gutted.

I also look forward to the results (seeing as everyone seems to hate them for some reason). I have been dabbling with LEDs for a couple of years now, and I can say that 'Royal Blue' (450nm) LEDs (minimum 1w types) are great for nurturing cuttings and seedlings - I can happily get 8 -12 Jalapeno seedlings growing very healthily under 13x royal blue 1 watt LEDs, and even get them up to decent adult stage where they start to flower using a 42w dual-spectrum version I built (red, blue 50:50). I should also say that I made a 70w 650nm red lamp with 1 watt Luxeon star LEDs, but this performed very, very poorly - as the above comments would suggest - hence my interest in the 'professional' products.

Maybe it's worth testing the blue-only UFO's for young plants; I think LEDs at present are currently only powerful enough for small or young plants, and I'm sure you would get great results.

My first attempts at indoor growing were done using the same 90w UFO LED lights..

USELESS! Small plants and small under developed fruits all round!

Moved to a 400w HID and BOOM! Beautiful large plants with bundles of properly developed fruits!!

No testing required! Use your valuable time testing something else! LED's do not come close to the performance of HID lamps! The only reason they became so 'interesting' a few years ago is due to the outrageous and unfounded claims that the developers made about performance! ALL LIES!

Thanks for input Jon! Our initial findings match what you are saying, but in the interests of making everyone aware of LED lights performance we're going to continue our tests. It's best all round if we document our experiments and help everyone make good equipment choices, but thanks again for your comments. As you can tell from our product range, we'd back a HID light every time but with all these wild claims about it's easy to see how some people could be convinced to try LED's - hopefully our experiments can provide some guidance!

Insomnus

Posted July 17, 2012 at 3:34 pm

I have tried them - with little success.
I exchanged 6x400w HPS with 8 120w 3 colour LED (600wHPS 'supposed' equivalent).

The plants grew slowly, spindly, stretched and gave a very small harvest.
I brought back the HPS and kept the LED going as a boost. Within 1 year almost all had failed - nowhere near the 80,000 hours claimed.

In the future, when they are more reliable and cheaper they may be worth another shot - till then they are pretty useless.

The question most of us ask is. Do they perform as well as the 400w hps as stated by the manufacturer. The only test you should be doing is a side bye side test from start to finish using the same genetics for plant subjects. That is the only true indication of what product performs better.

Hi Richard, given our previous experience with LED's over the years, we're pretty dubious that these LEDs are capable of performing as well as the 400w HPS, but we'll be doing a number of impartial tests and are more than happy to be proved wrong this time! We've got a number of tests lined up over the coming months, one of which will be pitting identical genetics cuttings against each other under LEDs vs Fluoro's vs HPS. This set of experiments will be running for quite a while it seems!

martyn

Posted July 17, 2012 at 11:18 am

I look forward to reading your results as i have been looking at led lights for a while now but there are so many to choose from. Good Luck